Correlation between comE expression levels and transformation rates of Streptococcus pneumoniae
AIM: To investigated the effect of comE on S. Pn transformation. METHODS: ComE-defective strains of S. Pn were constructed. The wild S. Pn strains and their comE-defective derivations were subjected to natural transformation and CSP-induced transformation. Transformation rates were calculated at different time stages and the mRNA expression levels of come were detected by FQ-PCR. RESULTS: For comE-defective strain, the transformation rate was 0, whether in natural or CSP-induced state, and the mRNA expression level of comE was accordingly undetectable. Whereas, for wild tyep S. Pn R6, the natural trans-formation rate peaked at the A550 of about 0.3, and the correlation coefficient between comE mRNA level and the transformation rate was 0.244. Similarly,D39 underwent transformation with the induction of different concentrations of CSP. The transformation rate was the highest with CSP concentration of 100μg/L, higher than that of 10 and 1000 μg/L. After 10-min induction with CSP at the concentration of 100 μg/L, the mRNA level of comE was significantly higher than that of basal level (P<0.05). When CSP concentration was at 10 and 1000μg/L, comE mRNA levels at different times were not well correlated with corresponding transfor-mation rates. Under the concentration of 100 μg/L, the correlation coefficients between comE mRNA expression level and the corresponding transformation rate were 0.9966, 0.7950 and 0.9984 at 0, 10 and 20 min, respectively. CONCLUSION : ComE is an essential gene for natural transformation and CSP-induced transformation, but no obvious correlation between the transformation rate and the comE mRNA expression level. The optimal concentration of CSP inducing transformation is 100 μg/L, at which the transformation rate is notably correlated with the basal comE mRNA level.
streptococcus pneumoniaetransformation, bacterialcomEreal time fluorescence quantification pulymerase chain reaction
NETL
NSTL
万方数据
维普
